Impact of the environmental conditions on the efficiency of earth-to-air heat exchangers under various configurations

Abstract

In the present paper, the impact of local climatic conditions on the efficiency of earth-to-air heat exchangers (EAHEs) is investigated by experiments. Four cases of EAHEs were considered: (1) a simple EAHE, (2) an EAHE with solar protection at the upper parts, (3) an EAHE with a chimney effect at the outlet, and (4) an EAHE with a fan at the inlet. The values of air temperature and relative humidity at the inlet, as well as at the outlet of the exchanger, were determined. For Cases 1 and 2, the lowest value of ΔT was -9 °C. However, the highest values were 11.9 and 12.5 °C for Cases 1 and 2, respectively. For Cases 3 and 4, the values of ΔT were equal to 7 and 12.5 °C, respectively. For the hygrometry and in Case 1, the difference in the relative humidity (ΔRH) has been increased by 13% and then decreased by 30%. Case 2 provided an increase in ΔRH by 47%. However, an increase of ΔRH by 43% followed by a decrease by 47% was observed in Case 4. Finally, Case 4 yielded a drying tendency and a stable decrease in ΔRH by 30% during almost all day. The use of a fan allowed the most significant control and reducing the impact of external climatic conditions.